Atomic Scale Simulations of Arsenic Ion Implantation and Annealing in Silicon
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AT&T Bell Laboratories, Rm. 1E332, 600 Mountain Ave., Murray Hill, NJ-07974
ABSTRACT We present results of multiple-time-scale simulations of 5, 10 and 15 keV low temperature ion implantation of arsenic on silicon (100), followed by high temperature anneals. The simulations start with a molecular dynamics (MD) calculation of the primary state of damage after 10ps. The results are then coupled to a kinetic Monte Carlo (MC) simulation of bulk defect diffusion and clustering. Dose accumulation is achieved considering that at low temperatures the damage produced in the lattice is stable. After the desired dose is accumulated, the system is annealed at 800 'C for several seconds. The results provide information on the evolution for the damage microstructure over macroscopic length and time scales and affords direct comparison to experimental results. We discuss the database of inputs to the MC model and how it affects the diffusion process. INTRODUCTION The manufacturing of VLSI devices is based on the implantation of dopants and recovery of the lattice structure by annealing at high temperature [1]. During annealing the defects produced by the implantation interact with the dopants. This process results in transient enhanced dopant diffusion (TED) [2,3,4]. It has been observed that at high dose and energy extended defects are produced that, as they
evaporate induce transient enhanced diffusion [5]. The critical number of displaced atoms necessary to produce these extended defects is reached at different doses for different ions masses and energies [6]. The minimum dose for {311} defect formation with 40 keV Si implantation in Si is approximately 5x1012 cm-2 [4]. This minimum dose has been observed to increase as the energy of the ion decreases. Therefore, at very low energies and dose{311} defects are not present and still transient enhanced diffusion occurs [7]. Doses as low as 1012 cm 2 for 180 keV Si implant induce transient B diffusion. However, for doses lower than 1013 cm-2 the enhancement in the diffusivity is almost constant [8]. Modeling of these phenomena requires methods that allow for long time scale calculations as well as large sizes. Recently Jaraiz et al. have shown that a hybrid between binary collision approximation models and Monte Carlo simulations gives results in very good agreement with experiments for 40 keV Si implantation in (001) Si and posterior annealing at high temperatures [9]. In this paper we describe a coupling between molecular dynamics simulations and Monte Carlo models in order to give a better insight to the mechanisms involved in the production and diffusion of defects in Silicon. We will present first the results obtained for single As cascade events on Silicon at different energies. We explain how the connection with Monte Carlo simulations is made and the parameters 45 Mat. Res. Soc. Symp. Proc. Vol. 396 01996 Materials Research Society
considered in this simulation. The last part of this communication will be a study of the influence of the ion dose in the recombination fa
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